Garage doors and the like are well known in the art. Indeed, it is well known in the art that garage doors usually require to be connected to a counterbalancing system for counterbalancing the weight of the door in order to decrease the force required to open the door and also safely facilitate its closing from a raised to a lowered position. Counterbalancing systems can be found in many other types of cable-operated doors, such as slidable truck doors for example.
It is also known in the art that a widely used type of counterbalancing system generally comprises a pair of spaced apart cable drums connected to corresponding cables, each cable being in turn connected to a lower opposite side edge of the garage door. The cable drums are usually mounted on an overhead shaft which is supported above the door opening and is connected to one or more torsion springs which are each fixed to the shaft at one end, and operatively secured to a fixed structure such as the wall, or a wall bracket for example, at the other end, so that the cable drums are biased to rotate in a direction which winds the cables onto the drums and counteracts the weight of the door connected to the cables. The torsion springs are adjusted to properly balance the weight of the door so that minimal opening and closing efforts are required, either manually or when motor controlled.
It is also known in the art that conventional, low cost adjustment devices used for the above-mentioned type of counterbalancing system, and widely utilized in the garage door industry, are generally cylindrical “collars” commonly referred to also as “plugs” (or “cones”) which are connected to the ends of the torsion springs and are thus mounted on the aforementioned shaft for adjusting the deflection of the springs to preset the torsional (or counterbalancing) force of the spring.
In operation, torque is transferred between the torsion spring, overhead shaft, and plugs which operatively connect the shaft to the spring, in order to counterbalance the weight of the garage door. Usually, each torsion spring is fixed to the overhead shaft at one end, by means of a plug known as a “winding plug”, and operatively secured to the wall via a bracket at the other end, by means of another plug known as a “stationary plug”.
One could envisage that, although very unlikely, it might happen that one of the elements (e.g. spring, of the counterbalancing mechanism may undergo a failure, leading to the garage door falling which is undesirable.
There have been many attempts to come up with braking devices which are used for slowing descent of a garage door and/or immobilizing the garage door in the event of a failure in its counterbalancing mechanism.
Known in the art is American patent application No. US 2002/0069685 A1 naming SCHIKS as inventor and published on Jun. 13th, 2002, which describes a drop-catch mechanism. The drop-catch mechanism is used for preventing a door leaf of an overhead door from falling down upon breakage of a balancing spring thereof. The mechanism comprises an input member for coupling with a balancing spring of the overhead door. The mechanism also comprises a ratchet wheel for coupling with a winding axle carrying the door leaf of the overhead door. The mechanism also comprises a pawl and means for moving the pawl form a free position that allows rotation of the ratchet wheel to a catching position that blocks rotation of the ratchet wheel. The means for moving the pawl are configured such that, in use, breakage of a balancing spring coupled to the input member causes the pawl to move from the free position to the catching position. The mechanism is characterized in that the means for moving the pawl from the free position into the catching position comprise a positive mechanical drive extending from the input member to the pawl.
Also known to the Applicant are the following U.S. patents and patent application which describe various devices for use with doors: U.S. Pat. Nos. 229,983; 603,237; 636,645; 826,284; 1,196,714; 1,863,961; 2,463,344; 2,546,081; 2,555,560; 2,878,865; 3,236,348; 3,842,892; 3,895,539; 4,116,314; 4,125,142; 5,257,685; 5,494,093; 5,706,552; 5,971,055; 6,070,641; 6,079,524; 6,102,480; 6,401,792; 6,431,619; and 2002/0170688 A1.
However, some of these devices are generally quite bulky; inherently elaborate; difficult to use, install, and/or maintain; and/or result to be cost ineffective.
Therefore, there is a need for a simpler, more compact, easier to use, easier to maintain, and/or more cost effective braking device than what is available in the prior art for stopping downward movement of a cable-operated door, such as garage doors and the like, in the event of a failure in the counterbalancing system of the door (for example, failure of one of the counterbalancing springs and/or failure of one of the elements connected to the counterbalancing springs).